Year	Percent
1991	69.704
1992	69.684
1993	69.362
1994	69.092
1995	68.823
1996	68.632
1997	68.576
1998	68.29
1999	68.091
2000	67.721
2001	67.641
2002	67.549
2003	47.137
2004	47.309
2005	47.216
2006	47.503
2007	46.808
2008	46.453
2009	46.072
2010	46.189
2011	43.034
2012	47.114
2013	43.416
2014	40.613
2015	39.606
2016	37.511
2017	37.623
2018	37.499
2019	37.398
2020	37.26
2021	37.112
2022	36.963